The drop coming down has hit another droplet launched from the spout and splashed out in mid-air causing a floating splash.
40% acetic acid solution with green dye dropping into black dyed water. Frosted perspex behind droplet with Speedlite 430EXII (1/64th power) with Orange Gel pointed down and Vivitar 285 (minimum power) pointed up with blue gel, flashes sat on top of each other. Fired with manual push button trigger wired into pc-sync hot-shoes.